Great Black-backed Gull (Larus marinus)

(last update: July 12, 2015)

Jean-Michel Sauvage (France)
Morten Helberg (Norway)
Nils Helge Lorentzen (Norway)
Mars Muusse (Netherlands)

Great Black-backed Gull (Larus marinus) 4CY, July 30 2014, IJmuiden, the Netherlands.

Immature bird in complete moult: P4/P7. PMS=23. Active moult in other feather tracts as well, prominent in coverts which are replaced for fresh grey-based feathers with fine vermiculation. Old P10 with large mirror and P9 with mirror; old 3rd gen secondaries with adult-like pattern, no vermiculation along edges.